Modern vehicles typically have one or more diagnostic systems, generally having separate computer control modules to control various functions of the vehicle. Some examples include power train control module (PCM), engine control module (ECM), a transmission control module (TCM), Anti-locking brake system (ABS), and an air bag control module. The vehicle diagnostic systems often have self-diagnostic capability to detect and alert the driver of problems the vehicle may be encountering. When a problem is found, a diagnostic trouble code or DTC, is set within the computer's memory. DTCs are as general or as specific as the manufacturer desires. Different vehicle models may have different sets of DTCs, including DTCs that report the same problem via different DTCs.
Further complicating matters, the E.P.A. (Environmental Protection Agency) has instituted the Onboard Diagnostics II (OBD II) system to diagnose and alert a driver to problems with a vehicle's emissions system. The OBD II system is required for all 1996 and newer vehicles. This system monitors the vehicle's emissions and if it detects any problems, the OBD II system will turn on the “Check Engine” light or the “Malfunction Indicator Lamp” (MIL), located on the instrument panel of the vehicle. Traditionally, the MIL or the Check Engine light is lit when a problem causes emissions from the vehicle to exceed the federal guidelines. Further, the OBD II system generates its own set of DTCs to assist a technician in detecting the specific problem that gave rise to the illumination of the MIL.
To retrieve and decipher DTCs, an auto repair technician needs a diagnostic tool. The diagnostic tool must, therefore, be connected to the vehicle's computer bus system to access and retrieve the DTCs. Scan tools are testing devices that interface with vehicle diagnostic systems to retrieve information from the various control modules. The scan tools are equipped to communicate in various communication protocols such as controlled area network (CAN), J1850 VPM and PWM, ISO 9141, Keyword 2000 and others. These communications protocols are specific to the various automobile manufacturers. The scan tool will help the technician to diagnose and repair the vehicle.
A low-cost alternative to the scan tool is a “code reader.” In 1998 Actron Manufacturing Corp. (a subsidiary of SPX Corporation) pioneered the first OBD II (On-Board Diagnostic) code reader. Similar to a scan tool, a code reader is a relatively basic device that links with one or more computer modules in a vehicle diagnostic system via the electronic control unit (ECU) of a vehicle computer network and reads any diagnostic trouble codes that are set by the vehicle's diagnostic system, and displays any DTCs on a display. Code readers are marketed to automobile hobbyists, professionals and non-professionals.
Further, there are some sensors or equipment in the vehicle that may be common to several systems in the vehicle. Thus, when there is a problem with one of those sensors, the numerous systems that share it may generate their own various DTCs to indicate that there is a problem. However, the various DTCs all note the same issue, which is redundant and leads to “duplicate DTCs.”
Therefore, the technician will not know at the outset that duplicate DTCs have been saved by the vehicle's computer. Although, the codes may look unique alphanumerically, they may point to the same problem. The only way to know for sure is to research each DTC and find its origin. Accordingly, the technician will have to perform additional research to decipher the list of DTCs. When duplicate DTCs are discovered, the technician may get frustrated with wasting his or her time and this will increase the cost to the consumer to repair the vehicle.
In addition, once the origin of the DTC is determined and the problem has been resolved, the technician has to delete the DTC from the computer's memory. When there are duplicate DTCs to clear, the technician, once again spends additional time clearing the duplicates.
Accordingly, it is desirable to provide an apparatus and method that can alert a technician that duplicate DTCs have been detected and removed so that diagnosis of the vehicle can be more accurate and less time consuming. It is also desirable to remove all the DTCs including any duplicates when the repairs are completed.